The objective of the proposed research is to empirically study the causes of household and family change in the U.S. since 1940 with consideration of the entire span of the adult life cycle. Using Public Use Sample microdata from the 1940, 1950, 1960, 1970, and 1980 Censuses of Population, the study examines household and family changes such as institutionalization of the elderly, living alone, cohabitation, female-headed families, and extended families. The determinants of the changes to be studied include: 1) variables such as income, age, marital status, number of children, race, sex, residence, and education, 2) changes in the means of above variables, 3) cohort shifts in household and family patterns; 4) changes in the effects of individual variables; and 5) residual changes over time controlling for changes in the composition of the population. Additionally, the study will analyze the structural determinants of the residual or net trends in household and family structures using aggregate timeseries measures of housing availability, consumer prices, social welfare programs, and sex ratios. The methods used to complete the goals of the project involve analysis of a combined sample from the five census years in which the additive and interactive effects of time are considered explicitly. Multinomial logit analysis is used to obtain estimates of the effects of the independent variables on the nominal measures of household/family/structure, and multivariate decomposition techniques are used to examine the compositional and processual components of changes over time in the household/family structure measure. Generalized least squares is then used to obtain estimates for the time-series models. The end result of the project will not only be to advance our empirical knowledge of the long-term trends and changes in family and household structure, but also to advance our theoretical knowledge by explicitly testing consumer demand, demographic composition, and cultural tastes explanations of family and household change.